---
title: Using npm packages in your projects
---

Once you have [installed a package][install-pkg] in `node_modules`, you can use it in your code.

## Using unscoped packages in your projects

### Node.js module

If you are creating a Node.js module, you can use a package in your module by passing it as an argument to the `require` function.

```javascript
var lodash = require('lodash');

var output = lodash.without([1, 2, 3], 1);
console.log(output);
```

### package.json file

In `package.json`, list the package under dependencies. You can optionally include a [semantic version][semver].

```json
{
  "dependencies": {
    "package_name": "^1.0.0"
  }
}
```

## Using scoped packages in your projects

To use a scoped package, simply include the scope wherever you use the package name.

### Node.js module

```js
var projectName = require("@scope/package-name")
```

### package.json file

In `package.json`:

```json
{
  "dependencies": {
    "@scope/package_name": "^1.0.0"
  }
}
```

## Resolving "Cannot find module" errors

If you have not properly installed a package, you will receive an error when you try to use it in your code. For example, if you reference the `lodash` package without installing it, you would see the following error:

```
module.js:340
    throw err;
          ^
Error: Cannot find module 'lodash'
```

- For scoped packages, run `npm install <@scope/package_name>`
- For unscoped packages, run `npm install <package_name>`

[install-pkg]: downloading-and-installing-packages
[semver]: about-semantic-versioning
